1. Field of the Invention:
This invention relates in general to airplanes which will take off and land on the tail section with the nose up and the fuselage vertical, and in particular to a landing gear assembly for use with such an airplane.
2. Description of the Prior Art:
Tail sitting airplanes have been known in the patented art and technical literature for some time. Prototypes have been developed. However, there has been no production of this type of airplane.
A tail sitting airplane lands and takes off on its tail section. The landing gear will extend rearward from the tail section for supporting the airplane in a vertical position. The fuselage will point upward during the takeoff and landing position.
Typically, the prior art designs show four landing gears, each with a castor type wheel. Each wheel is free to turn about an axis perpendicular to the wheel axle. This freedom to turn allows the airplane to be moved translationally along the ground while pointed vertically.
Castor type wheels present difficulties while landing. Castoring wheels are designed to allow the wheels to line up with the direction of motion so that they will roll and provide little resistance to the direction of motion. Little resistance to the direction of motion is essential to the safe landing of a tail sitter airplane. Any large amount of resistance to the direction of motion can cause the tail sitter airplane to tip over. Freedom of movement in the direction of motion is essential to a safe landing. If the castoring wheel should fail to align because of binding about the castoring axis, a high resistance could develop and cause the airplane to tip over.
Once the airplane has firmly landed, it is then desirable that the landing gear prevent translational motion for situations of high winds and/or sloping landing areas such as those that occur on the pitching and rolling decks of ships at sea. If wheel brakes are to be used to prevent this translational motion, they must be applied in exactly the right sequence, which is difficult to do. Otherwise, a disastrous tip over or rolling off of the deck could occur during a bouncy landing.